More and more attentions have been paid to network simulation with its important role in network research. Currently, terrestrial network simulation has been widely applied with its mature technique in many aspects. However, network simulation for satellite network with radio link and dynamic topology is still at an early stage. Constellation simulation and routing algorithm simulation have been two important research topics. After analyzing and utilizing relevant simulation software, a two-layered constellation simulation model is proposes in the thesis A simulation implementation of routing algorithm is also presented. Based on the implementation, a performance comparison of routing algorithm and two-layered constellation is given by simulation experiment. On the topic of constellation simulation, ranges of simulation software are investigated and OPNET and SaVi are selected as software solution. With the purpose of acquiring appropriate parameter value, a simulation model for satellite constellation is presented. The parameter determination is transformed into a multi-variable and multi-goal optimization problem. Based on problem simplifying, the optimized value is specified though the simulation using SaVi. On the topic of routing algorithm simulation, a satellite link simulation algorithm is designed according to the characteristics of dynamic topology and radio link. Moreover, its implementation in OPNET is provided. With the satellite link infrastructure, a simulation of routing algorithm is implemented in OPNET. Through simulation experiment and result analysis, it is testified that the routing algorithm has a good performance. In addition, a performance comparison between single-layered and double-layered constellation is made out by simulation, with the result of double-layered constellation being better. This research is an exploration of network simulation for satellite network. The result can be applied in the satellite network research, providing simulation support for protocol implementation and performance analysis.